BRITAIN could face legal action in Russia to halt the return of one of the Elgin Marbles on loan to the Hermitage museum in St Petersburg, it is feared.

Despite a pledge by David Cameron that the statue of Ilisos would be shipped back to the British Museum after the controversial show, at least one Russian political party plans to challenge ownership.

Greece claims Lord Elgin looted the marbles from the Parthenon in Athens in the early 19th century, and has long campaigned for their return.

It is thought the ultranationalist group will seek an injunction preventing the statue’s export back to the British Museum on January 18 as part of a bid to embarrass the West over opposition to the Russian invasion in Ukraine.

If successful, it would embarrass the Kremlin too.

The loan is believed to be part of a bid by the Foreign Office to hand isolated Russian leader Vladimir Putin “an olive branch”.

It follows accusations by Geoffrey Robertson QC, who with Amal Clooney is advising Greece on the marbles, that British Museum trustees were “giving President Putin a propaganda windfall at the very time sanctions are beginning to bite in order to deter him from a war that is causing hundreds of deaths in Ukraine”.

President Putin was expected to make a high-profile visit to the remarkable exhibit before Christmas.

This is a most important artistic and political gesture

Mikhail Piotrovskiy

Last night a senior Moscow legal source confirmed at least one party was considering “mounting a legal challenge to make a political point”.

He refused to name the party.

Despite vocal protests by the Greek government against the loan, it has said it will not demand that Russia returns the statue.

Instead, Athens will continue to push its case against Britain through Unesco.

On Friday, Greek Prime Minster Antonis Samaras branded the decision to loan one of the Elgin Marbles to Russia “an affront” to the Greek people.

He added that the controversial loan to Russia invalidated Britain’s past claim that the precious artefacts were too fragile to be moved.

But last night, Mikhail Piotrovskiy, director of the State Hermitage museum, dismissed Greek outrage.

“This is a most important artistic and political gesture,” he said, at a meeting of the Union of Russian Museums.

The risk of the statue not being returned was always a real fear, with British Museum trustee Patience Wheatcroft admitting that board members were concerned the piece might never come back when the loan was first discussed.

"There is always a risk that someone will do something untoward,” she said, “but we decided it was a very unlikely event and that there would be sufficient pressure to ensure that the object was returned.”